Notice to Contractors

The Montgomery County Council recently enacted a comprehensive revision to the County Noise Control Ordinance (Chapter 31B, Montgomery County Code), including changes to the provisions concerning noise from construction activities.

GENERAL ORDINANCE STANDARDS
(Non-construction related)

Maximum allowable sound levels, measured at the nearest receiving property line, are 65 dBA

(A-weighted decibels) during daytime hours and 55 dBA during nighttime hours, for residential receiving properties (67 dBA daytime and 62 dBA nighttime for non-residential receiving property). Mixed Use Zones are considered residential.

• "Daytime" means from 7 a.m. to 9 p.m. weekdays and 9 a.m. to 9 p.m. weekends and holidays.
• "Nighttime" means from 9 p.m. to 7 a.m weekdays and 9 p.m. to 9 a.m. weekends and holidays.
• "Receiving Property" means any property where people live or work and where noise is heard.

CONSTRUCTION EXEMPTION AND STANDARDS

"Construction" means temporary activities directly associated with site preparation, assembly, erection, repair, alteration, or demolition of structures or roadways. Construction Noise levels must be measured on a receiving property, but no closer than 50' from the noise source.

From 7 a.m. to 5 p.m. Weekdays, Construction Noise Levels must not exceed:

• 75 dBA without a "Noise Suppression Plan".
• 85 dBA with a "Noise Suppression Plan".
• "Noise Suppression Plan" means a written plan to use the most effective noise suppression equipment, materials, and methods appropriate and reasonably available for a particular type of construction.

At all times other than 7 a.m. to 5 p.m. weekdays, the general standards specified above must be met.

For example: Assuming a residential or mixed-use receiving property, construction noise levels from 5 p.m. to 9 p.m. weekdays and from 9 a.m. to 9 p.m. weekends and holidays must not exceed 65 dBA. From 9 p.m. to 7 a.m. weekdays and 9 a.m. on weekends and holidays, the standard is 55 dBA (this is unchanged from the previous ordinance).

Construction activities are also subject to the "Noise Disturbance" provisions of the Ordinance. Examples of Noise Disturbances are delivering materials or equipment, or loading or unloading in a residential area, or operating construction equipment with audible back-up warning devices during Nighttime Hours.

Summary - Construction Noise

Measured at nearest receiving property, but no closer than 50' from the noise source.

Weekdays (Monday - Friday), 7 a.m. to 5 p.m.

Without Suppression Plan: 75 dBA

With Suppression Plan: 85 dBA
5 p.m. to 9 p.m. :  65 dBA
9 p.m. to 7 a.m. :  55 dbA

Saturday, Sunday, Holidays

9 a.m. to 9 p.m.:  65 dBA
9 p.m. to 9 a.m.:  55 dBA

In the majority of circumstances in the County, the Receiving Property will be considered residential. In cases where the nearest receiving properties are non-residential, the standards will be 67 dBA/Daytime and 62 dBA/Nighttime, except from 7 a.m. to 5 p.m. weekdays, when the higher construction exemption prevails.

While a Noise Disturbance, as defined by the Ordinance, could conceivably occur at any time, it is most likely to happen during the Nighttime Hours. The most common complaint involves back-up beepers, and can be avoided by employing lawful alternatives to audible devices.

The Department of Environmental Protection is currently developing Regulations for Noise Suppression Plans, as required by the revised Ordinance. In general, such plans will involve equipment selection and maintenance, scheduling and reasonable care in planning and conducting operations. Often, noise suppression measures can be fabricated on-site using materials at hand.

As a point of reference, two persons, speaking in normal tones of voice at a distance of three feet, will generate about 63 dBA between them. Therefore, normal, fully intelligible conversation would be possible at the receiving property line of a site generating 65 dBA or less. By comparison, for normal, intelligible speech at a distance of about ten feet between speakers, the background sound would have to be 55 dBA or less.

Most equipment manufacturers, and especially those who produce or market in Europe or Asia, will have detailed noise performance specifications for their products. Many also provide silencing packages, both design and retrofit.

Copies of the revised Ordinance will be mailed upon request. If there are any questions or comments, please do not hesitate to contact the Office of Environmental Policy and Compliance at 240-777-7770.